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  • C07D471/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00
  • C07D471/02—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00 in which the condensed system contains two hetero rings
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  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D215/00—Heterocyclic compounds containing quinoline or hydrogenated quinoline ring systems
  • C07D215/02—Heterocyclic compounds containing quinoline or hydrogenated quinoline ring systems having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen atoms or carbon atoms directly attached to the ring nitrogen atom
  • C07D215/16—Heterocyclic compounds containing quinoline or hydrogenated quinoline ring systems having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen atoms or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
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  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
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  • H10K50/14—Carrier transporting layers
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Definitions

• the present invention relates to pyrido[3,2-h]quinazolines and/or 5,6-dihydro derivatives thereof, methods for their production and doped organic semiconductor material in which these quinazolines are employed.
• the performance characteristics of (optoelectronic) electronic multilayered components were determined from the ability of the layers to transport the charge carriers, amongst others.
• the ohmic losses in the charge transport layers during operation are associated with the conductivity which, on the one hand, directly influences the operating voltage required, but, on the other hand, also determines the thermal load of the component.
• the thermal load of the component is associated with the conductivity which, on the one hand, directly influences the operating voltage required, but, on the other hand, also determines the thermal load of the component.
• bending of the band in the vicinity of a metal contact results which simplifies the injection of charge carriers and can therefore reduce the contact resistance. Similar deliberations in terms of organic solar cells also lead to the conclusion that their efficiency is also determined by the transport properties for charge carriers.
• n-doping For a long time, a major problem in n-doping was that only inorganic materials were available for this process. However, using inorganic materials has the drawback that the atoms or molecules used can easily diffuse in the component due to their small size and thus can impede a defined production of sharp transitions from p-doped to n-doped areas, for example.
• the diffusion should play an inferior role when using large, space-filling, organic molecules as dopants as circuit crossing processes are only possible when higher energy barriers are overcome.
• a metal complex as n-dopant for doping an organic semiconductor matrix material to change the electrical properties thereof is known in which the connection relative to the matrix material represents an n-dopant.
• Ultraviolet photoelectron spectroscopy is the preferred method to determine the ionisation potential (e.g. R. Schlaf et al., J. Phys. Chem. B 103, 2984 (1999)).
• IPES inverse photoelectron spectroscopy
• E ox or reduction potentials E red are the solid state potentials.
• E red oxidation potentials
• CV cyclic voltammetry
• the dopant functions in n-doping as an electron donor and transmits electrons to a matrix which is characterised by a sufficiently high electron affinity. That means that the matrix is reduced.
• the charge carrier density of the layer is increased.
• an n-dopant is able to release electrons towards a suitable matrix with electron affinity and thereby increase the charge carrier density and, as a consequence thereof, the electroconductivity depends in turn on the relative position of the HOMO of the n-dopant and the LUMO of the matrix in relation to one another.
• the HOMO of the n-dopant is positioned above the LUMO of the matrix with electron affinity, an electron transfer can take place. If the HOMO of the n-dopant is arranged beneath the LUMO of the matrix with electron affinity, an electron transfer can likewise take place, provided that the energy difference between the two orbitals is sufficiently small to allow for a certain thermal population of the higher energy orbital. The smaller this energy difference, the higher the conductivity of the resulting layer should be. However, the highest conductivity can be anticipated in the case that the HOMO level of the n-dopant is higher than the LUMO level of the matrix with electron affinity. The conductivity can be measured conveniently and is a measure of how well the electron transmission from donor to acceptor functions, provided that the charge carrier mobilities of different matrices can be compared.
• the conductivity of a thin-film sample is measured by the 2 point method.
• contacts made from a conductive material e.g. gold or indium tin oxide, are applied to a substrate.
• the thin film to be examined is applied to a large surface area of the substrate such that the contacts are covered by the thin film.
• the current subsequently flowing is measured.
• the conductivity of the thin-film material results from the resistance thus determined.
• the 2 point method is admissible when the resistance of the thin film is substantially higher than the resistance of the leads or the contact resistance. This is in the experiment ensured by a sufficiently large distance of the contacts and thus, the linearity of the voltage-current characteristic can be checked.
• a dopant having the structure Ia can be employed in an advantageous manner as dopants for an organic matrix material, as such a dopant solves the diffusion problem described above. For this reason, a dopant having the structure Ia
• the ionisation potential in the gas phase of the dopant having the structure Ia is 3.6 eV.
• the corresponding ionisation potential of the solid can be estimated in accordance with Y. Fu et al. (J. Am. Chem. Soc. 2005, 127, 7227-7234) and is about 2.5 eV.
• the conductivities should be improved when using the matrix materials.
• a semiconductor material should be made available which exhibits an increased charge carrier density and effective charge carrier mobility as well as an improved conductivity.
• the semiconductor material should show a high thermal stability which results, for example, from higher glass transition temperatures, higher sublimation temperatures and higher decomposition temperatures.
• R 3 is selected from H, substituted or unsubstituted, alkyl with C 1 -C 20 , aryl and heteroaryl;
• pyrido[3,2-h]quinazolines and/or 5,6-dihydro derivatives thereof can be employed as matrix materials in doped organic semiconductor materials and then lead to improved conductivity results.
• pyrido[3,2-h]quinazolines and/or 5,6-dihydro derivatives can be produced in accordance with a method comprising the following steps:
• R 1 , R 2 , R 3 and R 4 are defined as above in claim 1 .
• potassium hydroxide and/or potassium tert-butoxide is used as the base.
• chloranil is employed for the oxidation of the 1,4,5,6-tetrahydropyrido[3,2-h]quinazoline.
• a doped organic semiconductor material comprising at least one organic matrix material which is doped with at least one dopant, wherein the matrix material is a pyrido[3,2-h]quinazoline and/or 5,6-dihydro derivative thereof.
• the matrix material can be reversibly reduced.
• the matrix material is breaking down into stabile, redox inactive components during a reduction by means of the dopant.
• the dopant can be a metal complex.
• the metal complex preferably has a structure I which is disclosed in patent application DE102004010954 (corresponds to WO05086251):
• M is a transition metal, preferably Mo or W;
• the dopant has the following structure Ia:
• the dopant is an organic compound with a sufficiently high oxidation potential (HOMO).
• the dopant is an alkaline and/or alkaline earth metal, preferably caesium.
• the organic semiconductor material according to the invention has an energy level for the lowest unoccupied molecule orbital (LUMO) which differs by 0 to 0.5 V from the ionisation potential (HOMO) of the dopant, preferably by 0 to 0.3 V, particularly preferably by 0 to 0.15 V.
• LUMO lowest unoccupied molecule orbital
• HOMO ionisation potential
• One embodiment is characterised in that the matrix material has a LUMO energy level which is lower than the HOMO of the dopant. “Lower” means in this case that the LUMO energy level has a smaller numerical value than the HOMO energy level. As both variables are given as negative values starting from the vacuum level, this means that the absolute value of the HOMO energy value is smaller than the absolute value of the LUMO energy value.
• the concentration of the dopant is 0.5 to 25 percent by weight, preferably 1 to 15 percent by weight, particularly preferably 2.5 to 5 percent by weight.
• An organic light-emitting diode is also according to the invention, comprising a semiconductor material according to the invention as well as benzylidene hydroquinolinones of the structure 5.
• pyrido[3,2-h]quinazolines and/or 5,6-dihydro derivatives thereof can be employed as redox dopable matrix materials which can be doped with metal complex dopants, in particular those having the structure I.
• the matrix materials employed according to the invention for the semiconductor material further exhibit an improved thermal stability in comparison with the prior art which is in particular attributable to higher glass transition temperatures and higher sublimation and decomposition temperatures.
• the matrix material preferably has an evaporation temperature of at least 200° C.
• the matrix material preferably has a decomposition temperature of at least 300° C.
• 2,4-Disubstituted quinolinones of the structure 4 can be obtained in a three-step synthesis, starting from 2,4,6-triphenylpyrylium salts 1 and cyclohexanedione, via the step of the 8-oxo-1-benzopyrylium salts 3 (cf. Scheme 1).
• 8-Oxo-1-benzopyryliumperchlorate has already been described by Zimmermann et al. (T. Zimmermann, G. W. Fischer, B. Olk, M. Findeisen: J. prakt. Chem. 331, 306-318 [1989]).
• the synthesis via the tetrafluoroborate 3 was newly developed in the present invention.
• 2,4-Disubstituted quinolinones of the structure 4 have been found as being particularly useful synthesis components for the construction of N-heterocycles. It is known that the condensation of quinolinones and aldehydes can be employed for the formation of benzylidene derivatives. Applying this reaction to the 2,4-disubstituted quinolinones in accordance with Scheme 2 leads to new benzylidene hydroquinolinones 5.
• Step 2 Synthesis of 5,6,7,8-tetrahydro-8-oxo-2,4-diphenyl-1-benzopyryliumtetrafluoroborate 3a
• Step 5 Synthesis of 1,4,5,6-tetrahydro-2,4,7,9-tetraphenylpyrido[3,2-h]quinazoline 6a
• the ivory-coloured precipitate is extracted by suction, washed with distilled water and rewashed with 30 ml of ethanol. After drying under high vacuum, 2 g (92.8%) of almost white, cotton-like powder with a melting point of 142-144° C. (no clear melt) is obtained.
• the TGA results in a melting point of 139° C.
• the DSC a T g of 74° C.
• the product shows a broadened NH band at 3385 cm ⁇ 1 as well as in low intensity a band at 1687 cm ⁇ 1 which can be assigned to an isolated C ⁇ N band.
• the slightly more intensive band at 1630 cm ⁇ 1 is attributable to the dihydroquinoline ring.
• the cream-coloured polder (1.35 g) is washed with 50 ml of chloroform in portions. 100 ml of 6% potassium carbonate solution is added to the chloroform solution and it is vigorously stirred. The aqueous phase is separated in a separatory funnel, shaken twice with 25 ml of chloroform each time and discarded. The combined chloroform phases are washed with distilled water and dried after separating the aqueous phase over anhydrous potassium carbonate. The dried, light yellow chloroform solution is filtered with a pleated filter and 50 ml of cyclohexane is added. The chloroform is widely removed by distillation on a rotavapor under reduced pressure.
• the obtained cream-coloured microcrystalline powder is extracted by suction, washed with cyclohexane and dried under high vacuum: 3.10 g of ivory-coloured microcrystalline product (91%) with a melting point of 298-299° C. is obtained.
• the TGA shows the melting peak of 299° C.
• the 2 nd heating process shows a T g of 103° C.
• the NH band at 3385 cm ⁇ 1 and the C ⁇ N bands at 1687 cm ⁇ 1 and 1630 cm ⁇ 1 of the starting material have disappeared, instead a new, split band can be observed in low intensity at 1591 cm ⁇ 1 or 1581 cm ⁇ 1 , respectively.
• the black residue which is interspersed with white crystals is washed on a sintered-glass filter with 400 ml of chloroform in portions.
• the brownish-yellow filtrate is dried over anhydrous sodium sulphate, filtered and evaporated to dryness.
• the cream-coloured residue is dissolved in 50 ml of chloroform with slight heating and filtered in 100 ml of cyclohexane.
• the light yellow solution is concentrated to half of its volume, during which an ivory-coloured, cotton-like precipitate is deposited. This is extracted by suction, washed with a little cyclohexane and diethyl ether and dried under high vacuum: 0.82 g (87.5%) of a microcrystalline white powder with a very exact melting point of 327° C.
• the reduction is reversible. It is not possible to measure an oxidation potential within the window available in MeCN.
• the sublimination temperature of 8a is 259° C. and thus is markedly higher than the bench mark of 200° C.
• a solution of 1.5 g of potassium hydroxide (36.7 mmol) in 15 ml of distilled water is added to the suspension of 5 g of 6,7-dihydro-2,4-diphenylquinolin-8(5H)-one (16.7 mmol).
• the resulting suspension is stirred in a sealed round-bottomed flask at room temperature for 1 d, neutralised with glacial acetic acid and stirring at room temperature is continued for 30 min.
• the precipitate is extracted by suction, washed with distilled water and dried.
• the ivory-coloured powder is suspended in 80 ml of methanol and stirring at room temperature is continued for 30 min.
• the precipitate is extracted by suction, washed with methanol and diethyl ether and dried under high vacuum: 3.2 g of ivory-coloured powder (47%) with a melting point of 175-185° C. (decomposition).
• the product shows the CO valence vibration band typical for chalcones at 1675 cm ⁇ 1 .
• Step 5 Synthesis of 1,4,5,6-tetrahydro-2,7,9-triphenyl-4-p-toluylpyrido[3,2-h]quinazoline 6b
• the product shows a broadened NH band at 3418 cm ⁇ 1 as well as in low intensity a band at 1625 cm ⁇ 1 which can be assigned to an isolated C ⁇ N band.
• Step 6b Synthesis of 5,6-dihydro-2,7,9-triphenyl-4-p-toluylpyrido[3,2-h]quinazoline 7b
• the aqueous phase is shaken twice with 25 ml of chloroform each time and then discarded.
• the combined chloroform phases are washed with distilled water, dried over anhydrous potassium carbonate, filtered and 50 ml of cyclohexane is added.
• the chloroform is widely removed by distillation under reduced pressure.
• the obtained powder is extracted by suction, washed with a little cyclohexane and dried under high vacuum: 2.1 g (85%) of ivory-coloured microcrystalline product with a melting point of 261° C. and a T g of 109° C. is obtained.
• Step 7 Synthesis of 2,7,9-triphenyl-4-p-toluylpyrido[3,2-h]quinazoline 8b
• the filtrate is dried over anhydrous sodium sulphate and filtered.
• the solution is evaporated to dryness under reduced pressure.
• the cream-coloured residue is dissolved in 50 ml of chloroform with slight heating and filtered in 100 ml of cyclohexane.
• the light yellow solution is concentrated to half of its volume under reduced pressure, during which an ivory-coloured, cotton-like precipitate is deposited.
• the precipitate is extracted by suction, washed with cyclohexane and diethyl ether and dried under high vacuum.
• 1.5 g (75%) of a microcrystalline white, cotton-like powder with a melting temperature of 261° C. is obtained.
• a T g could not be detected by means of DSC.
• the 1 H-NMR spectrum in CDCl 3 only includes the signals of 5,6-dihydro-2,4,7,9-tetraphenylpyrido[3,2-h]quinazoline.
• the signals of the methylene protons of the starting material at 3.07 (dd, 2H) and 2.95 (dd, 2H) have disappeared, i.e., the dehydrogenation has been completed.
• the sublimination temperature of 8b is 272° C. and thus is markedly higher than the bench mark of 200° C.
• a glass substrate is provided with contacts made from indium tin oxide. Subsequently, a layer of 7a doped with a dopant of the structure Ia is formed on the substrate.
• the doping concentration of the dopant Ia is 5 mol %.
• the conductivity of the layer at room temperature is 4.13*10 ⁇ 5 S/cm.
• a glass substrate is provided with contacts made from indium tin oxide. Subsequently, a layer of 8a doped with a dopant of the structure Ia is formed on the substrate.
• the doping concentration of the dopant Ia is 5 mol %.
• the conductivity of the layer at room temperature is 1.84*10 ⁇ 5 S/cm.
• a glass substrate is provided with contacts made from indium tin oxide. Subsequently, a layer of 7b doped with a dopant of the structure Ia is formed on the substrate.
• the doping concentration of the dopant Ia is 5 mol %.
• the conductivity of the layer at room temperature is 2.05*10 ⁇ 5 S/cm.
• a glass substrate is provided with contacts made from indium tin oxide. Subsequently, a layer of 8b doped with a dopant of the structure Ia is formed on the substrate.
• the doping concentration of the dopant Ia is 5 mol %.
• the conductivity of the layer at room temperature is 2.76*10 ⁇ 5 S/cm.
• a Comparative Example 7 was performed analogous to the procedure of Examples 3 to 6, but the BPhen known from literature was used instead of the matrix material 7a, 8a and 7b, 8b, respectively.
• the obtained conductivity of the layer is 4*10 ⁇ 9 S/cm.
• a substrate made from glass is provided with indium tin oxide contacts.
• the layers spiro TTB doped with the p-dopant 2-(6-dicyanomethylene-1,3,4,5,7,8-hexafluoro-6H-naphthalen-2-ylidene)malononitrile (50 nm, 1.5 wt %)/N,N′-di(naphthalen-2-yl)-N,N′-diphenylbenzidine (10 nm), N,N′-di(naphthalen-2-yl)-N,N′-diphenylbenzidine doped with the emitter iridium(III) bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate) (20 nm, 10 wt %)/2,4,7,9-tetraphenylphenanthroline (10 nm)/8a doped with Ia (60 nm, 8 wt %)/A1 (
• Example 6 An OLED structure as in Example 6 was produced. In this, the undoped electron transport layer 8a is used instead of the electron transport layer 8a n-doped with Ia. This OLED has the following operational parameters at 100 cd/m 2 : 18.2 V and 7.4 cd/A.

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